Give any website a WebMCP interface

Introduced WebMCP support to Cloudflare Workers, enabling websites to expose tools for AI agents via an edge-injected bridge script. This involves adding a `<script>` tag to HTML responses and serving a bridge script from the edge. The bridge registers tool packs (e.g., Content Credentials, Site MCP Server) with the browser's `document.modelContext`. The Content Credentials pack scans images for C2PA metadata, and the Site MCP Server pack allows agents to interact with the origin's MCP server. This extends edge computing to facilitate agent-browser interaction.